Arson is one of the most difficult crimes to solve. However, contrary to popular opinion, evidence is usually recoverable from the scene of the crime. In over half of all the suspicious structure fires that happened between 1991 and 1995 there was no flame damage outside of the room of origin. Further, in 40 percent of cases, there is no damage beyond the immediate area of origin. The problems of investigation of arson is shown in the arrest percentages; the range is usually between 15 and 20 percent of all cases, which is typical for major property crimes which usually go unwitnessed.

Arson and the Law

In terms of prosecuting the crime, arson is divided into three degrees, in decreasing order of seriousness. First and second degree arson are considered and treated as felonies, while third degree is only a misdemeanor. Also, in many countries (Great Britain being a major exception), an arsonist is charged with murder if anyone died because of the fire.

In the American criminal justice system, arson remains one of the hardest crimes to solve. According to FBI statistics, between 15 and 19 percent of all arson offenses have been cleared every year since 1980. This rate is much lower than the rate for violent crimes such as murder, rape or aggravated assault. The rates tend to be lower in cities rather than in rural areas for crimes like arson, most likely because such crimes are usually committed by members of the community.

46% of all arson cases solved in 1996 were commited by individuals under age 18, and in one third of all cases the perpetrator is under 15. This stands as the highest percentage of juvenille involvement in any FBI indexed crime. Usually, arson committed by juveniles involves fires set to things other than structures or vehicles.

Motives

Most common, arson is committed because of insurance fraud. However, other motives include setting fires for spite, as a method for concealing other crimes, pyromania, and various mental disorders. Pyromania has many causes, including alcoholism or various personal circumstances such as a poor home life or unemployment. The disorder may take years to manifest itself, but the most obvious signs of pyromania are an obsession with matches or lighters.

Investigational Techniques

When investigating an alleged arson case, the investigator will employ many methods to solve the crime. Usually this includes analyzing burn patterns, determining how the fire spread including patterns and what specifically was damaged, photographing the scene and taking samples of fire debris for analysis. This last aspect is particularly crucial; if accelerants can be detected at the scene, the case for arson is obviously bolstered and is very necessary in order for the prosecutor to go to trial with a good case. Sampling is very difficult, because the investigator must determine what objects to sample which have the greatest likelihood of yielding evidence of flammable liquids. Due to limits of time, resources, and budget constraints as well as the possibility of contamination of evidence after the crime as been committed makes this part of the job particularly difficult. However, in recent years, the development of dogs specifically trained to detect latent accelerants has made this portion of investigation somewhat easier.

Sources:

http://www.cmi.k12.il.us/Urbana/projects/apple/service/department/types/arson.html
http://www.sosfires.com/The%20Truth%20About%20Arson.htm  All statistics from the FBI.
http://www.houstonals.org/Highlights/Nov%202001/Arson.htm

The malicious burning of a dwelling house or outhouse of another man, which by the common law is felony; the malicious and voluntary firing of a building or ship.

Wharton.

⇒ The definition of this crime is varied by statues in different countries and states. The English law of arson has been considerably modified in the United States; in some of the States it has been materially enlarged, while in others, various degrees of arson have been established, with corresponding punishment.